Variable pressure apparatus



Feb. 18, 1936. E, CRANE E A z mm ss VARIABLE PRESSURE APPARATUS Filed Dec. 29, 1932 2 Sheets-Sheet 0. v. wnms v 5y ATTORNEY E T M V M 5 Feb. 18, 1936. E. J. CRANE ETAL 2,030,966

VARIABLE PRE S SURE APPARATUS Filed Dec. 29, 1932 2 Sheets-Sheet 2 Patented Feb. 18, 1936 UNITED STATES PATEN oFFic Waters, Cranford, N.

J., assignors to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application December 29, 1932, Serial No. 649,354

5 Claims.

This invention relates to variable pressure apparatus, and more particularly to a fluid pressure actuated press and a control system therefor.

The primary object of this invention is to pro- 5 vide an improved variable pressure apparatus and a reliable and efiicient automatic control system therefor.

In accordance with one embodiment of this invention there is provided a hydraulically actum ated press of the variable pressure type having a pair of cylinders opening into each other, one of the cylinders being larger in diameter than the other and having a piston carrying a ram, the other cylinder having a piston carrying an intensifier plunger. A pressure fluid transmission system is connected to the cylinders and the opening therebetween for introducing fluid pressure thereinto to actuate the pistons comprising a manually operable valve for controlling the 20 system, and a system of fluid pressure controlled valves operated sequentially in response to an actuation of the manually operable valve to release pressure normally holding the ram in its normal position, direct pressure to the space be-- '25 tween the pistons to actuate the ram through part of its pressure stroke, build up a predetermined pressure therebehind, releasing the holding pressure on the intensifier plunger, and then actuating the plunger to further increase the pressure 30 behind the ram for the remainder of its pressure stroke. When the ram reaches the end of its stroke and upon a predetermined pressure being exerted thereagainst the system of valves is automatically actuated to cause pressure to be di 5 rectedto return the ram and the intensifier plunger to their normal positions.

Other features and advantages of this invention will more fully appear from the following detailed description taken in connection with 40 the accompanying drawings, wherein Fig. l is a partial diagrammatic fragmentary view of a hydraulically actuated press of the variable pressure type and one embodiment of the control system of this invention for controlling 45 the operation of the press, the elements being shown in low pressure position, and Fig. 2 is a partial diagrammatic fragmentary view similar to Fig. l, but illustrating the elements at the end of an operating stroke of the 5 press and at the instant that a predetermined pressure is developed in the press cylinder-to cause pressure to be directed to return the -ram and the intensifier plunger to their normal positions.

Referring now to the drawings there is illustrated fragmentarily and in partially diagrammatic form a hydraulically actuated press of the variable pressure type having main and supplemental cylinders lll and H within which are carried vertically reciprocable pistons I2 and I3, respectively, of different diameters and areas. The piston I2 is integral with a ram M, which may carry at its lower end a punch, or other machine tool, (not shown) for operating on material associated with a die (not shown) carried upon the bed of the press (not shown). Integral with the piston I3 is a plunger ll guided in a cylindrical passage l8 interconnecting the cylinders l0 and II. The cylinder H, piston l3, and. plunger I! form an intensifier which functions at a predetermined point in the operation of the press to provide for the introduction of a greatly increased pressure into the maincylinder l0 and against the ram It for the final operation of the punch or other tool carried by the ram lfl, on the material associated with the die. The pistons I2 and I3 are actuated by motive fluid, for instance, oil, under suitable pressure, supplied to the cylinder Ill at opposite ends of the piston l2 through ports I9 and 20 and to the cylinder ,H at-opposite ends of the piston I3 through ports 2| and 22. The motive fluid for actuating the pistons l2 and I3 is supplied to the cylinders I0 and II through the ports I9, 20, 2! and 22 from a plurality of motor driven constant delivery pumps 25, 26, and 21 of a known type,- shown diagrammatically, or any suitable source of motive fluid which will deliver a fluid at a constant rate. The pump 25 is a high capacity pump, and the pumps 26 and 21 are small capacity supplementary pumps delivering a small volume of fluid as compared to that of the main pump 25, and the several pumps may be supplied with oil from a common reservoir, or from individual reservoirs, (not shown) 0 by oil lines 28 connected to inlet ports of the pumps.

The efiect of the motive fluid from the pumps 25, 26, and 21 on either the pistons J2 and I3 of the press, or the control system, to complete 5 an operating cycle thereof is controlled by a system of two-position piston valves, interconnected by a plurality of fluid lines. The control system includes a manually operable valve 29, fluid pressure controlled valve 32, 33, and 34, and blow-through valves 35, 36, and. 31. The manually operable valve 29 includes a balanced piston plunger 38 which is normally maintained in its upper position, as shown, by a compression spring 39 operatively associated with a stem lects to remove his foot from the treadle after an actuation thereof.

It is to be understood that in the normal condition of the system it is filled with fluid. The normal position of the ram 4 and intensifier plunger l1 and the condition of the control system before the start of an operating cycle thereof is as shown in Fig. 1 of the drawings. At this period the main pump 25 and supplementary pumps 26 and 21 are all operating and constantly delivering motive fluid. The ram M is held in its upper position and prevented from falling under its own weight by the pressure of the fluid under the piston l2 in the cylinder I9 and that in the fluid line connecting the port l9 and a suitable valve 4| included in the fluid line to the port l9 which permits fluid to flow unrestricted in the direction of the arrow and prevents the flow thereof in the opposite direction, except under the influence of a predetermined minimum pressure. The intensifier plunger at this time is held in its upper position by the pressure of the fluid directed into the supplemental cylinder ll under the piston l3 through the port 2|, the fluid line to which is connected to the supplementary pump 21 in a manner to be presently described. The plunger 38 of the valve 29 is in its upper position, as is a differential area piston plunger 43, and piston plungers 44 and 45 of the fluid pressure controlled valves 32, 33, and 34, respectively, which plungers are maintained in their upper position by compression springs 46 operatively-associated therewith. A piston 48 of the blow-through valve 36 is in its extreme left position determined by a stop collar 49 abutting an outside surface of the valve. The blow-through valve 35 has a piston plunger 50 which at this time is held in its extreme right position by a compression spring 5| acting against the left end thereof. Also a piston plunger 52 of the blow-through valve 31 is in its lower position due to a compression spring 531 acting against the upper end thereof. Connected to the outlet line of the main pump 25 is a suitable relief valve 54 which is set to open at a predetermined pressure somewhat above the maximum pressure desired in the system and sufficiently low. to protect the associated control system and press from destructive pressures.

With the elements of the control system in the described positions, and as'shown in the drawings (Fig. 1), motive fluid from themain pump 25 is being by-passed through the fluid pressure controlled valve 32 and the manually operable valve 29 to the fluid reservoir of the pump, the fluid first being directed to a port 56 of the valve 32 I and out a port 51 thereof to a port 58 of the valve 29 and thence to the reservoir. At this time motive fluid from the pump 25 can also pass tothe reservoir through port 56, passages 62, 63, 64, and 65 of the plunger 43 of the valve 32, a port 68 of the latter valve, the port 58 of the valve 29 and to the reservoir. The purpose of the passages 62, 63, 64, and 65 of the diilerential area piston plunger 43 will be made apparent hereinafter. The port 56 of the valve 32 at this time is also in communication with the valve 4| below the ram l4 by way of a port 69 of the valve 32, port 10 of the valve 33, and port thereof. Also m'otive fluid from the fluid line interconnecting the ports II and I9 is being constantly directed by way of a port 13 of the blow-through valve 31 against the lower end of the plunger 52 thereof, but not with enough force to overcome the action of the spring 53, which is overcome only during the return of the control system to its normal position which will be referred to hereafter.

The supplementary pump 21 is directing motive fluid by way of a port 15 of the blow-through valve 36 and against the plunger 48 therein, thus holding the plunger in its left position. Also at this time the pump 21 is constantly directing motive fluid, under suitable pressure, by way of ports I6 and 11 of the fluid pressure controlled valve 34, the port 2| of the supplemental cylinder ll of the press and against the lower end of the piston l3 to holki the intensifier plunger in its upper position and preventing it from moving downwardly under its own weight. Motive fluid from the pump 21 can only escape from the system through a suitable relief valve 18 associated with the outlet line from the pump and communicating with the reservoir. The supplementary pump 26 at this time is constantly directing motive fluid to a' port 19 of the blow-through valve 35, through a plurality of passages 82 of the plunger 50, port 83 of the latter valve, a port 84 of the valve 28, and thence to the reservoir. All motive fluid lines connected to the pump 26, therefore, at this time contain relatively low fluid pressure and consequently the pressure on the top of the the cylinders H) and II, respectively, or other fluid leaks in the system, have been suitably com- I pensated for is as follows: The plunger 38 of the manually operable valve 29 is moved downwardly to its lower position by an actuation of the mechanical non-repeat mechanism and the foot treadle, hereinbefore mentioned (not shown). In this position of theplunger 38 the port 53 of the valve 29 is cut off from thereservoir and consequently the fluid from the main pump 25 cannot reach the reservoir by this path. The only other path for the fluid from the pump 25 is through the ports-56 and 69 of the valve 32, the

ports 10 and ll of the valve '33, the-valve 4| and the port l9 of the main cylinder lll'below the ram |4. Therefore, the pressure of the fluid delivered by the main pump 25 rises quickly and due to the back pressure directed to the top annular differential' area of the piston plunger 43 of the valve 32 by way of the passage 62, which top area is larger than the adjacent annular area therebelow of the plunger, it is moved to its lower position against the action of its associated spring 46.

This position of the plunger 43 will be maintained until the plunger 52 of the blow-through valve 31 is moved upwardly during the return of the control system to its normal position, when fluid under suitable pressure is admitted to the valve 32 under the plunger 43 by way of'ports and 86 of the valves 31 and 32, respectively. During the downward movement of the plunger 43.

the fluid under the lower end thereof escapes through the port 86 of the valve 32 and a port 89 of the manually operable valve 29 which is open to the reservoir when the plunger 38 is in its lower position. When the port 58 is closed. off the port 84 is also closed off, thereby closing off the fluid from the supplementary pump 26 from the reservoir and thereby causing the pressure of the fluid delivered by this pump to rise and tending to'force the plunger 58 of the blow-through valve 35 to its left position. When the plunger 38 of the valve 29 is in its lower position a port 98 thereof is uncovered and connected to the outlet port of the pump 25, thus permitting communication between the supplementary pump 26 and the main pump 25. This permits fluid from the pump 25 to be directed by way of the port 98 to the fluid line connecting the pump 26 and the port 19 of the valve 35 and assist in moving the plunger 58 thereof to its left position.

The supplementary pump 26 is now closed off from the reservoir by way of the port 19, passages 82, ports 83 and 84, with the result that the plunger 58 will remain in its left position, even after the non-repeat mechanism permits the plunger 38 of the valve 29 to move to its upper position again and uncover the port 84. This results in an increased pressure in the line from the outlet port of the pump 26 which is also connected to the valve 33 above the top of the plunger 44 thereof by a port 9 I, and as the pressure increases the plunger 44 is moved to its lower position, the pressure rising until it reaches a point corresponding to the setting of a suitable relief valve 92 associated with the outlet line from the pump, thus maintaining the plunger 44 in its lower position.

The movement of the plunger 44 to its lower position cutsoflf the fluid from the main pump 25 to the valve 4| below the ram I4 by way of the ports 18 and H of the valve 33 and opens communication to the inlet port 28 of the main cylinder I8 of the press by way of the port 18 and a port of the valve 33, ports 96 and 91 of the valve 34, and through a valve 98, similar to the valve-4|, to the port 28 and the main cylinder I8 above the piston I2. At the same time the inlet port 22 of the supplementary cylinder II of the press is connected to the main pump 25 by way of the ports 18 and 95 of the valve 33. The mechanical non-repeat mechanism, hereinbefore mentioned, which is designed to hold the plunger 38 of the manually operable valve 29 depressed for a predetermined period of time has by now ope. ated so that the plunger 38 has moved back to its upper position through the action of the spring 39.

From the foregoing description it will be apparent that the plungers 43 and 44 of the valves 32 and 33, respectively, will remain in their lower position and the plunger 58 of the blow-through valve 35 in its left position after the return of the plunger 38 of the valve 29 to its upper position.

The motive fluid directed into the main cylinder through the port 28 will force the ram I4 downwardly, but the intensifier plunger I1 will remain in its upper position due to the higher pressure of the fluid being directed into the supplementary cylinder II below the piston I3, by way of the port 2| from the pump 21. Upon the pressure in the main chamber I8 above theram I4 reaching a predetermined amount, substantially the setting of the relief valve 18 associated with the outlet side of the pump 21, the pressure is directed by way of a port I88 of the blowthrough' valve. 36 against the plunger 48 thereof and it is moved to the right against the pressure of the fluid being directed against the plunger at its left end through the port 15 from the pump 21. This permits fluid under pressure to be admittedto the top of the plunger 45-01? the valve 34 by way of a port I8I of the valve 36 and a port I82 of the valve 34 and the plunger 45 moves to its lower position. It is to be understood that the design of the valve 36 is such that the port II of the valve 36 is closed oiffrom the reservoir by-way of ports I83 and I84 'of the valve, the latter port being connected to the reservoir, be-

fore being connected to the port I88 by the mentary pump 21, is cut off from the port 2I' of the supplementary cylinder I I and the latter port is connected by way of the port 11 'and a port I89 of the valve 34 to the reservoir, the latter port being connected to the reservoir. Also in I the lower position of the plunger 45 the ports 91 r and 96 of thevalve 34 are cut off from the line to the main pump 25 and consequently the port 28 of the main cylinder I8 is likewise cut off. Thereafter the only passage which is open to the entire output of motive fluid from the main pump 25 is to the supplementary cylinder II above the intensifier piston I3 by way' of the ports 56 and 69 of the valve 32 and the ports 18 and 95 of the valve 33-and thence to the port 22 of the supplementary cylinder. The intensifier plunger I1 then moves downwardly, raising the pressure in the main cylinder I8 above the ram I4 and consequently forcing the ram downwardly under greatly increased pressure and thus causing the punch 'or other tool carried by'the ram to perform its operation on the material associated with the die carried on the bed of the.

press, the extent of the downward movement of the ram being limited by a suitable stop member (not shown). The elements of the control system at the end of an operating stroke of the ram I4 are positioned as shown in Fig. '2. The operation of the .control system to cause the return stroke of the ram I4 will now be described. When a predetermined pressure, for example, 600 tons, is reached in the main cylinder I8, the plunger 58 of the blow-through valve 35 is moved to the right by back pressure directed by way of the port 28 of the main cylinder and "a port II4 of the valve 35 against the left end'of the plunger 58. This movement of the plunger 58 cuts off theport I81 from the port I88 which latter port is connected to the reservoir and permits the fluid under pressure to be directed by way of a port II5 of the valve 35, the port I85 of the valve 34 and a port II6 of the valve 33 to the space below the plungers 45 and 44, respectively. 3 simultaneously the supplementary pump 26' is connected to the reservoir by way of the port 19, passages 82 of the plunger 58,'and

the port 83, all of the valve 35, and thence to the port 84 of the manually operable valve 29 to the reservoir; The pressure above the plunger 44 is therefore released pressure only and the plunger moves upwardly under the influence of its associated spring 46.

The upper port 22 of the supplementary cylinder I I is now connected to the reservoir by way of the port 95 and a port II I both of the valve 33, the latter port being connected to the reservoir. Also at this time the main pump 25 is in communication with the lower port I9 of the main cylinder II] by way of the ports 56 and 69 of the valve 32 and the ports I0 and II of the valve 33 and the valve M. The upper port 20 of the main cylinder I0 is still out off from the main pump 25 but the pressure in the cylinder Ill drops rapidly due to the port 22, of the supplementary cylinder II, being connected to the reservoir and eventually falls below that sufficient to maintain the piston 48 of the blowthrough valve 35 in its extreme right position against the pressure of the supplementary pump 21. The piston 48, therefore, moves-to its left position and opens the space above the plunger 45 of the valve 34 to the reservoir by way of the port I02 of the valve 34 and the ports I03 and I 64 of the valve 35 and the plunger 45 moves upwardly under the influence of its associated spring 45.

With the main pump 25 in communication with the port I9 of the main cylinder, in the manner just described, the ram I4 moves upwardly and due to the valve 93, arranged between the port 91 of the valve 34 communicating with the port '96 thereof and also with the ports 95 and I" of the valve 33, the latter port being connected to the reservoir, and the port 20 which is similar to the valve M at the port I9, pressure is also exerted against the intensifier plunger I'I, thus the ram and plunger move up rapidly. To avoid forming a pressure vacuum in the line from the port 2| of the supplemental cylinder II during the upward movement of the intensifier plunger I'I this line is connected to the reservoir by means of a unidirectional or check valve I20 through which fluid may be drawn from the reservoir.

When the ram I4 reaches the top of its return stroke, the position shown in the drawings, an enlargement on the ram engages a positive stop surface I2 I, while a reduced upper portion of the plunger II engages the inner upper surface of the cylinder I I. Immediately the pressure in the line connecting the main pump 25 with the port I9 is raised sufiiciently to force the piston plunger 52 of the return stroke blow-through valve 31 upwardly and connect the ports 13 and 85 of the valve, thereby admitting pressure through the port 85 and under the plunger 43 to move it to its upper normal position. This position of the plunger 43 opens the line from the main pump 25 to the reservoir, in the manner previously described. As a consequence the pressureagainst the lower end of the plunger 52 is lowered sufficiently to permit the plunger to move downthe actuation of a single manually controlled valve to start the cycle.

Although the invention has herein been illustrated and described in connection with one embodiment thereof as applied to a particular type of pressure apparatus, it is to be understood that the novel features thereof are capable of various other applications limited only by the scope of the appended claims.

What is claimed is:

1. A variable pressure apparatus for actuating a pressure element comprising a'pair of cylinders of different diameters having a passage interconnecting the same, pistons reciprocable in the cylinders, the piston of largest diameter carrying a pressure element, the piston of smallest diameter carrying a plunger reciprocable in the interconnecting passage, a liquid pressure transmission system connected to both ends of each of the cylinders and the interconnecting passage for introducing liquid pressure thereinto to actuate and return each of the pistons comprising a manually operable valve for controlling the system, and a system of liquid pressure controlled valves operated sequentially in response to an actuation of the manually operable valve to direct the pressure to actuate the pressure element piston, build up a predetermined pressure behind the element, actuating the plunger piston to further increase the pressure behind the element, and then directing the pressure liquid for returning the pistons to their starting positions, said pressure systern comprising a large capacity pumpand a small capacity pump, said pressure controlled valves being normally in position to direct liquid from said small capacity pump'for holding said plunger piston in retracted position, said pressure piston being held in retracted position by a minimum pressure valve and during the operating stroke liquid from the large capacity pump being directed first to the operating face of the pressure piston and subsequently solely to the plunger piston.

2. A variable pressure press comprising a pair of cylinders opening into each other, pistons reciprocable in the cylinders, one carrying a ram and one a plunger, a liquid pressure transmission system connected to both ends of each of the cylinders and to the opening therebetween for introducing liquid pressure thereinto to actuate and return each of the pistons comprising a manually operable valve for controlling the system, and a system of liquid pressure controlled valves including means for causing pressure to be directed to the system of valves in response to an actuation of the manually operable valve for operating them sequentially to actuate the ram piston through part of the pressure stroke of the ram, build up a predetermined pressure behind the ram, and to hold the plunger piston in its idle position during said movement of the ram, and means for holding the pressure built up behind the ram, releasing the holding pressure on the plunger piston, actuating the plunger piston to further increase the pressure behind the ram for the remainder of its pressure stroke, and then directing the pressure liqu d for returning the pistons to their starting positions.

- 3. A variable pressure press comprising a pair of cylinders of different diameters opening into each other, pistons reciprocable in the cylinders, the piston of largest diameter carrying a ram, and the piston of smallest diameter carrying a plunger reciprocable in the opening therebetween, a liquid pressure transmission system connected to both ends of each of the cylinders and to the opening therebetween for introducing liquid pressure thereinto to actuate and return each of the pistons comprising a manually operable valve for controlling the system, said valve effective when moved from its normal position to an operative position to control the system through a predetermined portion of its operating cycle and upon being returned to its normal position controlling the remainder of the cycle, which latter portion includes the operation of said ram and plunger, and a system of liquid pressure controlled valves operating in a predetermined sequence including means for directing pressure to the ram cylinder to actuate the ram piston through part of the pressure stroke of the ram and to build up a predetermined pressure behind the ram, and pressure directing means for causing the plunger to be held stationary during said movement of the ram, actuating the plunger piston to further increase the pressure behind the ram for the remainder of its pressure stroke, and then directing the pressure liquid for returning the pistons to their starting positions.

4. A variable pressure apparatus for actuating a ram comprising a pair of cylinders of difierent diameters having a passage interconnecting the same, pistons reciprocable in the cylinders, the piston of largest diameter carrying a ram, the piston of smaller diameter carrying a plunger reciprocable in the interconnecting passage, a liquid pressure transmission system connected to the cylinders and to the interconnecting passage ior introducing liquid pressure thereinto to actuate the pistons comprising a manually operable valve for controlling the system, and a system of liquid pressure controlled valves including means normally effective to introduce liquid pressure into one end of each of the cylinders to hold the ram and the plunger in their idle positions, means responsive to an actuation of r for holding the plunger in its idle position and directing pressure to the opposite end of the plunger cylinder for actuating the plunger piston to further increase the pressure behind the ram for the remainder of its pressure stroke.

5. In a fluid pressure apparatus, a work cylinder and piston, a source of fluid pressure, a valve normally spring held to direct fluid from said source to one side of said piston to operate the piston to its non-working position, means to move said valve to direct fluid to the other side of said piston comprising a manual valve operable to direct fluid pressure to move said first valve against said spring, and an auxiliary source of fluid pressure effective to maintain said first valve in operated position after said manual valve is returned to normal.

EDWARD J. CRANE. DANIEL V. WATERS. 

